Grey's Anatomy, Season 6

Meredith:
[voiceover] It's the most important job in the world. You probably should need a license to do it, but then most of us wouldn't even pass the written exam. Some people are naturals. They were born to do it. Some have other gifts. But the good news is biology dictates you don't have to do it alone. You can waste your whole life wondering, but the only way to find out what kind of parent you'd be is to finally stop talking about it and just do it.